In industrial and manufacturing processes, many products require heating at high temperatures, such as 300.degree. F. to 1000.degree. F., in order to drive off water vapor. Products such as plywood, veneer board, ceiling tile, and gypsum board require drying in large volumes, which is often accomplished in continuously fed, roller-type drying ovens. Typically, the oven temperature is held constant, while the boards are continuously fed through the oven on powered rollers.
Such powered rollers conventionally are held in position by bearing assemblies mounted on an oven frame. Because the oven temperatures are too high for oil or grease lubricated bearings, self-lubricating carbon/graphite bearings are normally used. Because such bearings require periodic replacement, the carbon/graphite material is usually press-fit into a steel sleeve in the form of a replaceable cartridge. The replaceable cartridge is designed to be locked into the bearing assembly with a spring or wire clip, so that a replacement can be made quickly without having to remove nuts and bolts. On the driven end of the rollers, the replaceable cartridge conventionally is split into two halves which can be taken apart during replacement, thus avoiding the need to remove the roller drive chain and sprocket. However, because the steel sleeve and carbon/graphite bushing are split, it is not possible to press-fit the bushing into the steel sleeve. As a result, the carbon/graphite bushing is not held securely and can turn with the journal. Turning with the journal causes the outside circumference of the carbon/graphite bushing to wear and eventually the bushing will fall out of the sleeve. The present invention is an improvement over our co-pending patent application Ser. No. 646,842, now U.S. Pat. No. 4,560,290, filed 9-4-84.